Sure thing! We've got 23 and we're gonna multiply it by 28. That's the same as adding 23 to itself 28 times.
Step 1: 0 + 23 = 23
Step 2: 23 + 23 = 46
Step 3: 46 + 23 = 69
Step 4: 69 + 23 = 92
Step 5: 92 + 23 = 115
Step 6: 115 + 23 = 138
Step 7: 138 + 23 = 161
Step 8: 161 + 23 = 184
Step 9: 184 + 23 = 207
Step 10: 207 + 23 = 230
Step 11: 230 + 23 = 253
Step 12: 253 + 23 = 276
Step 13: 276 + 23 = 299
Step 14: 299 + 23 = 322
Step 15: 322 + 23 = 345
Step 16: 345 + 23 = 368
Step 17: 368 + 23 = 391
Step 18: 391 + 23 = 414
Step 19: 414 + 23 = 437
Step 20: 437 + 23 = 460
Step 21: 460 + 23 = 483
Step 22: 483 + 23 = 506
Step 23: 506 + 23 = 529
Step 24: 529 + 23 = 552
Step 25: 552 + 23 = 575
Step 26: 575 + 23 = 598
Step 27: 598 + 23 = 621
Step 28: 621 + 23 = 644

So, 23*28 = 644